Effects of Geometry of Wings Submerged in Turbulent Bluff-Body Wake

The effects of the aspect ratio, the sweep angle, and the leading-edge geometry of wings placed in a turbulent wake were investigated in wind-tunnel experiments at a chord Reynolds number of 105. The poststall lift enhancement due to the leading-edge vortex formation was studied at optimal locations in the wake. The effects of the strength of the leading-edge vortices, the ratio of the spanwise length scale of the incident vortex to the wingspan, and the degree of two-dimensionality of the wake-wing interaction were studied. The competition between the effects of the spanwise length scale of the incident wake and the strength of the leading-edge vortices determined the optimal aspect ratio, which was found to be around four. Increasing the sweep angle decreased the mean lift due to the decreased two-dimensionality of the vortex formation. Airfoils with sharp leading edge produced the strongest leading-edge vortices but further away from the wing surface, resulting in lower maximum lift. Relative to the performance in the undisturbed freestream, the increases in the stall angle and maximum lift coefficient were not significantly affected by the leading-edge shape.